Total glucosides of paeony induces regulatory CD4(+)CD25(+) T cells by increasing Foxp3 demethylation in lupus CD4(+) T cells

Pharmacological Mechanism of Chinese Medicine in Systemic Lupus Erythematosus: A Narrative Review

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder affecting multiple systems, characterized by the development of harmful autoantibodies and immune complexes that lead to damage in organs and tissues. Chinese medicine (CM) plays a role in mitigating complications, enhancing treatment effectiveness, and reducing toxicity of concurrent medications, and ensuring a safe pregnancy. However, CM mainly solves the disease comprehensively through multi-target and multi-channel regulation process, therefore, its treatment mechanism is often complicated, involving many molecular links. This review introduces the research progress of pathogenesis of SLE from the aspects of genetics, epigenetics, innate immunity and acquired immunity, and then discusses the molecular mechanism and target of single Chinese herbal medicine and prescription that are commonly used and effective in clinic to treat SLE.

A Review of the Potential Benefits of Herbal Medicines, Small Molecules of Natural Sources, and Supplements for Health Promotion in Lupus Conditions

The Latin word lupus, meaning wolf, was in the medical literature prior to the 1200s to describe skin lesions that devour flesh, and the resources available to physicians to help people were limited. The present text reviews the ethnobotanical and pharmacological aspects of medicinal plants and purified molecules from natural sources with efficacy against lupus conditions. Among these molecules are artemisinin and its derivatives, antroquinonol, baicalin, curcumin, emodin, mangiferin, salvianolic acid A, triptolide, the total glycosides of paeony (TGP), and other supplements such as fatty acids and vitamins. In addition, medicinal plants, herbal remedies, mushrooms, and fungi that have been investigated for their effects on different lupus conditions through clinical trials, in vivo, in vitro, or in silico studies are reviewed. A special emphasis was placed on clinical trials, active phytochemicals, and their mechanisms of action. This review can be helpful for researchers in designing new goal-oriented studies. It can also help practitioners gain insight into recent updates on supplements that might help patients suffering from lupus conditions.

The epigenetic regulation of the germinal center response

In response to T-cell-dependent antigens, antigen-experienced B cells migrate to the center of the B-cell follicle to seed the germinal center (GC) response after cognate interactions with CD4⁺ T cells. These GC B cells eventually mature into memory and long-lived antibody-secreting plasma cells, thus generating long-lived humoral immunity. Within GC, B cells undergo somatic hypermutation of their B cell receptors (BCR) and positive selection for the emergence of high-affinity antigen-specific B-cell clones. However, this process may be dangerous, as the accumulation of aberrant mutations could result in malignant transformation of GC B cells or give rise to autoreactive B cell clones that can cause autoimmunity. Because of this, better understanding of GC development provides diagnostic and therapeutic clues to the underlying pathologic process. A productive GC response is orchestrated by multiple mechanisms. An emerging important regulator of GC reaction is epigenetic modulation, which has key transcriptional regulatory properties. In this review, we summarize the current knowledge on the biology of epigenetic mechanisms in the regulation of GC reaction and outline its importance in identification of immunotherapy decision making.

DNA Methylation Sustains "Inflamed" Memory of Peripheral Immune Cells Aggravating Kidney Inflammatory Response in Chronic Kidney Disease

The incidence of chronic kidney disease (CKD) has rapidly increased in the past decades. A progressive loss of kidney function characterizes a part of CKD even with intensive supportive treatment. Irrespective of its etiology, CKD progression is generally accompanied with the development of chronic kidney inflammation that is pathologically featured by the low-grade but chronic activation of recruited immune cells. Cumulative evidence support that aberrant DNA methylation pattern of diverse peripheral immune cells, including T cells and monocytes, is closely associated with CKD development in many chronic disease settings. The change of DNA methylation profile can sustain for a long time and affect the future genes expression in the circulating immune cells even after they migrate from the circulation into the involved kidney. It is of clinical interest to reveal the underlying mechanism of how altered DNA methylation regulates the intensity and the time length of the inflammatory response in the recruited effector cells. We and others recently demonstrated that altered DNA methylation occurs in peripheral immune cells and profoundly contributes to CKD development in systemic chronic diseases, such as diabetes and hypertension. This review will summarize the current findings about the influence of aberrant DNA methylation on circulating immune cells and how it potentially determines the outcome of CKD.

Total glucosides of paeony: A review of its phytochemistry, role in autoimmune diseases, and mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniae Radix Alba (PRA, called baishao in China), the root of Paeonia lactiflora Pall., has shown a rich medicinal value for more than 2000 years. PRA is used in local medicine and traditional medicine for autoimmune diseases associated with inflammation. At present, total glucosides of paeony (TGP), the main active ingredient of PRA, has been developed into a preparation for the treatment of autoimmune diseases, as TGP exhibits the effect of regulating immunity, anti-inflammatory, and analgesic effects.

AIM OF THE REVIEW

TGP was developed and applied to inflammation-related autoimmune diseases in modern clinical practice. Based on its application in traditional prescriptions, this article reviews PRA's botany and phytochemistry (including its extraction process and quality control), and discusses the clinical application and pharmacological research of TGP as an anti-inflammatory drug from the perspective of ethnopharmacology. Additionally, we review modern pharmacological and molecular-target research on TGP and discuss the mechanisms of TGP in treating autoimmune diseases. Through a systematic literature review, we also highlight the clinical efficacy of TGP in the treatment of immune diseases, and provide a reference for the continued scientific development and quality control of TGP so that its wider application and clinical value can be fully realized.

MATERIALS AND METHODS

Literature search was conducted through the Web of Science, Baidu Scholar, ScienceDirect, PubMed, CNKI, and WanFang DATA using the keywords "Total glucosides of paeony", "Paeonia lactiflora Pall. ", "Paeonia veitchii Lynch", "Paeoniae Radix Alba or white peony", "Paeoniae Radix Rubra or red peony", "Paeoniflorin", "Albiflorin", "Autoimmune diseases", and their combinations. In addition, information was collected from relevant textbooks, reviews, and documents.

RESULTS

Approximately 15 compounds have been identified in TGP, of which paeoniflorin and albiflorin are the most common constituents. In recent years, studies have found that TGP and its main chemical components are effective in the treatment of autoimmune diseases, such as rheumatoid arthritis, psoriasis, oral lichen planus, and Sjogren's syndrome. TGP has a variety of pharmacological effects related to PRA traditional effects, including anti-organ-damage, anti-inflammatory, analgesic, antioxidant, cardiovascular, and nervous-system protection. Previously published reports on TGP treatment of autoimmune diseases have shown that TGP regulates intracellular pathways, such as the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathways. However, there is no standardized preparation method for TGP, and there is insufficient quality control of formulations. Many related pharmacological studies have not tested TGP components, and the validity of such pharmacological results requires further verification.

CONCLUSIONS

Modern pharmacological research on TGP is based on the traditional usage of PRA, and its folk medicinal value in the treatment of autoimmune diseases has now been verified. In particular, TGP has been developed into a formulation used clinically for the treatment of autoimmune diseases. The combination of TGP capsules and chemicals to treat autoimmune diseases has the effect of increasing efficacy and reducing toxicity. Based on further research on its preparation, quality control, and mechanisms of action, TGP is expected to eventually play a greater role in the treatment of autoimmune diseases.

Efficacy, Chemical Constituents, and Pharmacological Actions of Radix Paeoniae Rubra and Radix Paeoniae Alba

Radix Paeoniae Rubra and Radix Paeoniae Alba are the different characteristic forms of Paeonia lactiflora Pall. They are widely used as traditional Chinese medicines in clinical practices. This study analyzes the development history, efficacy, chemical compositions, and pharmacological effects of Radix Paeoniae Rubra and Radix Paeoniae Alba, and explores the causes of the similarities and differences of these two amalgams. It provides a basis for the clinical application of these two Chinese medicinal materials, and lays a foundation for further study of the pharmacological effects and the quality identification of Paeonia lactiflora Pall as it applies to traditional Chinese medicine.

[Total glucosides of paeony inhibits proliferation and promotes activation- induced cell death of mouse T cells in vitro]

OBJECTIVE

To investigate the effects of total glucosides of paeony (TGP) on the proliferation and activation-induced cell death of mouse T cells and the mechanism underlying the immunosuppressive effects of TGP.

METHODS

Purified total T cells isolated from the spleen of C57BL/6 mice were treated with TGP at 0, 50, 100, or 200 μg/mL and stimulated by anti-CD3/ CD28. Flow cytometry was performed to detect the cell death and the proliferation of CFSE-labeled T cells. The expression of Fas/FasL mRNA was detected using RT-PCR, and flow cytometry was used to analyze the expression of Fas/FasL proteins on activated T cells. Western blotting was used to detect the expression of Bcl-2 in the cells.

RESULTS

TGP treatment for 48 h significantly reduced the total number and percentage of viable T cells and dose-dependently lowered the percentage of divided T cells. TGP treatment obviously up-regulated the cellular expression of Fas mRNA, enhanced Fas expression on the surface of the T cells, and decreased the expression level of Bcl-2 protein in the cells.

CONCLUSIONS

TGP significantly inhibits proliferation and promotes activation-induced cell death of mouse T cell by increasing the expression of Fas and downregulating the expression of Bcl-2.

Total glucosides of paeony decreases apoptosis of hepatocytes and inhibits maturation of dendritic cells in autoimmune hepatitis

Total glucosides of paeony (TGP), an active mixture extracted from paeony root, has anti-inflammatory and immunoregulatory effects and is widely used for the treatment of autoimmune diseases such as rheumatoid arthritis. However, the role of TGP in autoimmune hepatitis (AIH) is still unknown. In this study, we aimed to investigate the effect of TGP in autoimmune liver disease (AILD) patients and in concanavalin A (Con A)-induced experimental autoimmune hepatitis (EAH). Changes in biochemical parameters of AILD patients showed that treatment with TGP exerts significant protective effects on liver function, as reflected by decreased levels of serum alanine transaminase, aspartate transaminase, γ-glutamyl transpeptidase and total bilirubin. In EAH mice, we found that pretreatment with TGP reduced the levels of serum liver enzyme levels, histopathological damage and hepatocyte apoptosis. Importantly, flow cytometry analysis showed that pretreatment with TGP reduced the infiltration of mature dendritic cells in the liver. In vitro, TGP pretreatment ameliorated the Con A-induced mitochondrial membrane potential decline, reactive oxygen species increase, and apoptosis increase in hepatocytes. In addition, the levels of Bax, Cleaved Caspase-3 and cytoplasmic Cytochrome C decreased during this process, whereas those of Bcl-2 and mitochondrial Cytochrome C increased. Therefore, TGP might decrease hepatocyte apoptosis through the mitochondrial apoptotic pathway. Moreover, the maturation of bone marrow dendritic cells was also inhibited by TGP treatment. In conclusion, TGP treatment ameliorates AIH by regulating hepatocyte apoptosis and DC maturation. TGP is a potential compound for AIH treatment.

Low expression and hypermethylation of FOXP3 in regulatory T cells are associated with asthma in children

The aim of the present study was to determine the expression and methylation levels of forkhead transcription factor P3 (FOXP3) in peripheral blood CD4⁺CD25⁺ regulatory T cells (Tregs) harvested from children with asthma, and to explore the pathogenesis of asthma. The percentages of CD4⁺CD25⁺FOXP3⁺ Tregs in CD4⁺ T lymphocytes from 15 children with asthma and 15 healthy controls were measured by flow cytometry, and FOXP3 mRNA expression in the CD4⁺CD25⁺ Tregs was measured by reverse transcriptase-quantitative PCR. In addition, the forced expiratory volume in one second (FEV1) was measured to determine lung function. The methylation statuses of 16 CpG sites in two regions of the FOXP3 gene's exon and intron were analysed with bisulfite-specific PCR and pyrophosphate sequencing. The differences in methylation levels between the asthma and control groups were compared. The percentage of CD4⁺CD25⁺FOXP3⁺ Tregs in CD4⁺ T lymphocytes and FOXP3 mRNA expression were significantly lower in children with asthma than in control children (P<0.05). The FOXP3 mRNA levels in children with asthma were positively correlated with FEV1 (P<0.001; r=0.895). The methylation levels in 12 of the 16 studied CpG loci of the FOXP3 gene, and of the 6th CpG locus in the exon regions, were significantly higher in the asthma group compared with the control group (P<0.05). In summary, low expression and hypermethylation of the FOXP3 gene in the peripheral blood were associated with the pathogenesis of asthma in children. Thus, the FOXP3 mRNA expression level can be used to predict the severity of asthma in children.

Anti-inflammatory and immunoregulatory effects of paeoniflorin and total glucosides of paeony

As a Traditional Chinese Medicine, Paeonia lactiflora Pallas has been used to treat pain, inflammation and immune disorders for more than 1000 years in China. Total glycoside of paeony (TGP) is extracted from the dried root of Paeonia lactiflora Pallas. Paeoniflorin (Pae) is the major active component of TGP. Our research group has done a lot of work in the pharmacological mechanisms of Pae and found that Pae possessed extensive anti-inflammatory and immune regulatory effects. Pae could inhibit inflammation in the animal models of autoimmune diseases, such as experimental arthritis, psoriatic mice and experimental autoimmune encephalomyelitis, and so on. Pae modulates the functions and activation of immune cells, decreases inflammatory medium production, and restores abnormal signal pathway. Pae could balance the subsets of immune cells through inhibiting abnormal activated cell subsets and restoring regulatory cell subsets. Pae could regulate signaling pathways (GPCR pathway, MAPKs /NF-κB patway, PI3K /Akt /mTOR pathway, JAK2 /STAT3 pathway, TGFβ /Smads, and etc.). TGP is composed of Pae, hydroxyl-paeoniflorin, paeonin, albiflorin and benzoylpaeoniflorin etc. Pae accounts for more than 40% of TGP. Like Pae, TGP has anti-inflammatory and immune regulatory effects. TGP has been widely used to treat autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriasis, allergic contact dermatitis, and etc. in China. Furthermore, TGP has some superior features with immune regulation, gentle effect, many indications and few adverse drug reactions. These findings suggest that TGP may be a promising anti-inflammatory and immune drug with soft regulation and has more superiority in the treatment of AIDs. Currently, TGP is used for the treatment of RA, SLE and other AIDs in more than 1000 hospitals in China, which obtained great social and economic benefits.

Total Glucosides of Paeony protects against collagen-induced mouse arthritis via inhibiting follicular helper T cell differentiation

BACKGROUND

The development of rheumatoid arthritis (RA) is related to germinal center (GC) response and autoreactive T cells, which mediate adaptive immunity and play an important role in stimulating the production of autoantibodies and pro-inflammatory cytokines by B cells and macrophages. Total Glucosides of Paeony (TGP) has anti-inflammatory, immunomodulatory and analgesic effects and is widely used to treat RA. However, few studies investigated whether the therapeutic effect of TGP is associated with the inhibition of autoimmune response.

PURPOSE

The aim of this study was to investigate the effects and mechanisms of TGP on RA.

STUDY DESIGN

Type II collagen-induced arthritis (CIA) mouse model was used, and TGP and paeoniflorin were intragastrically treated.

METHODS

DBA/1 mice were divided into 5 groups: control, model, positive drug (paeoniflorin) and high- and low-dose TGP group. After 21 days of intragastric administration, the pathological change, inflammation expression and molecular mechanism of each group of mice were detected by Micro-CT, histochemical analysis, ELLSA, Western blot, RT-qPCR and flow cytometry.

RESULTS

Our study found that TGP treatment effectively improved inflammation and joint destruction in CIA mice. It reduced the production of serum IgG2a and pro-inflammatory cytokines, including serum interleukin (IL)-21, tumor necrosis factor (TNF)-α and IL-6, and the phosphorylation of NF-κB p65 and STAT3 in a dose-dependent manner. More importantly, TGP could suppress the frequency of germinal center B cells and Tfh cells in the spleen.

CONCLUSION

TGP can not only improve symptoms, but also inhibit bone destruction. The therapeutic effect of TGP on CIA is mainly achieved by inhibiting spleen Tfh cell differentiation and GC formation through STAT3 signaling pathway.

Effects of glycyrrhizin on the pharmacokinetics of paeoniflorin in rats and its potential mechanism

Context: Paeoniflorin is reported to possess numerous pharmacological activities. Paeoniflorin and glycyrrhizin are always used together for the treatment of disease in China clinics; however, the drug-drug interaction between glycyrrhizin and paeoniflorin is still unknown. Objective: This study investigates the effects of glycyrrhizin on the pharmacokinetics of paeoniflorin in rats. Materials and methods: The pharmacokinetics of orally administered paeoniflorin (20 mg/kg) with or without glycyrrhizin pre-treatment (at a dose of 100 mg/kg/day for 7 days) were investigated in male Sprague-Dawley rats using LC-MS/MS. Additionally, Caco-2 cell transwell model and rat liver microsome incubation experiments were also conducted to investigate its potential mechanism. Results: The results showed that when the rats were pre-treated with glycyrrhizin, the C_max of paeoniflorin decreased from 59.57 ± 10.24 to 45.36 ± 8.61 ng/mL, and AUC_0-inf also decreased from 282.02 ± 35.06 to 202.29 ± 28.28 μg·h/L. The t_1/2 value of paeoniflorin decreased from 8.48 ± 2.01 to 5.88 ± 1.15 h (p < 0.05). The Caco-2 cell transwell experiments indicated that glycyrrhizin could increase the efflux ratio of paeoniflorin from 2.71 to 3.52, and the rat liver microsome incubation experiments showed that glycyrrhizin could significantly increase its intrinsic clearance rate from 53.7 ± 4.6 to 85.6 ± 7.1 μL/min/mg protein. Conclusions: These results indicated that glycyrrhizin could affect the pharmacokinetics of paeoniflorin, and it might work through decreasing the absorption of paeoniflorin by inducing the activity of P-gp or through increasing the clearance rate in rat liver by inducing the activity of CYP450 enzyme.

Total glucosides of paeony attenuates animal psoriasis induced inflammatory response through inhibiting STAT1 and STAT3 phosphorylation

ETHNOPHARMACOLOGICAL RELEVANCE

Psoriasis is an immune system meditated disease, especially T cells. It disturbed many people around the world and hard to therapy. Paeonia lactiflora Pall has been used as a medicine in china for thousands of years. Recent studies found that the main component of Paeonia lactiflora Pall can alleviates the immune response in many diseases. In this study, we researched the effects and possible mechanisms of total glucosides of paeony (TGP) on animal psoriasis.

AIM OF THE STUDY

To study the therapeutic effects and mechanisms of TGP in 5% propranolol cream-induced psoriasis in guinea pigs and Imiquimod (IMQ) cream-induced psoriasis in mice.

MATERIALS AND METHODS

The effect of TGP was evaluated using a psoriasis-like model of guinea pigs and mice. Ear thickness was accessed, and pathology injury was observed by H&E staining. The levels of serum IL-1β, IL-6, IL-12, IL-17, IL-23, TNF-α, and IFN-γ, skin IL-17A, IL-22 and orphan nuclear receptor (RORγt) mRNA expression, proliferating cell nuclear antigen (PCNA), total or phosphorylated signal transducers and activators of transcription (STAT1, STAT3) were determined by enzyme linked immunosorbent assays (ELISAs), real time PCR, immunohistochemical staining, and western blotting, respectively.

RESULTS

Compared with model group, TGP treatment decreased the ear thickness, improved pathology of psoriasis, alleviated IMQ-induced keratinocyte proliferation, reduced the inflammatory cytokine, and downregulated IL-17A, IL-22, and RORγt mRNA in mice. Further study indicated that TGP inhibited STAT1 and STAT3 phosphorylation in lesion skins of psoriasis-like mice.

CONCLUSIONS

TGP alleviates the symptoms of psoriasis-like guinea pigs and mice, and the possible mechanism may relate to inhibit T helper 17 (TH17) cell differentiation and keratinocytes proliferation by inhibiting STAT1 and STAT3 phosphorylation.

DNA methylation was involved in total glucosides of paeony regulating ERα for the treatment of female systemic lupus erythematosus mice

Total glucosides of paeony (TGP) is a bioactive compound extracted from paeony roots and has been used in therapy for autoimmune diseases. However the molecular mechanism of TGP in the therapy of autoimmune diseases remains unclear. ERα has a pro-inflammatory role in SLE disease. In this study, we found that TGP treatment significantly decreased the expression of ERα by up-regulating ERα promoter methylation levels. Further investigation revealed that treatment with TGP increased the expression of DNMT in lupus mice. We also used DNA methyltransferase inhibitors to verify whether DNA methylation was involved in these process. HE staining results showed that TGP can reduce renal injury in SLE mice. Moreover, cytokines including IFN-γ, IL6 and IL12 expression and dsDNA levels in serum were inhibited by TGP treatment. These findings indicate that TGP inhibits autoimmunity in SLE mice possibly by downregulate ERα expression, which may in turn be due to its ability to regulate the methylation status of the ERα promoter.

The Effectiveness and Safety of Total Glucosides of Paeony in Primary Sjögren's Syndrome: A Systematic Review and Meta-Analysis

Objective: To assess the effectiveness and safety of the total glucosides of paeony (TGP) on the treatment of primary Sjögren's syndrome (pSS) by conducting a meta-analysis. Methods: Eight databases were searched from their inception to December 10, 2018 for randomized controlled trials (RCTs). The Revman 5.3 software was used for this meta-analysis. Results: Nine RCTs which included 770 participants were identified. Pooled results showed that significant difference in Schirmer's test (P < 0.00001) comparing TGP with placebo (PBO). However, the pooled results displayed significant differences in salivary flow rate, Schirmer's test, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), serum γ-globulin, immunoglobulin G (IgG), IgA, IgM, and effective rate (P ≤ 0.01) in the co-administration of TGP with immunosuppressant (IS) compared with IS alone. Subgroup analyses revealed both heterogeneities in ESR and serum γ-globulin were eliminated, showing combined intervention of TGP + IS being more advantageous than single usage of IS (P < 0.00001). However, the advantage varied among three subgroups and showed a gradual weakening over time. Furthermore, our results showed statistical significance in Schirmer's test (P = 0.0006), when hydroxychloroquine (HCQ) was jointly applied, but not in the case of combined TGP with methotrexate (MTX) (P = 0.41). For the safety analysis, the most common adverse events (AEs) were diarrhea or gastrointestinal discomfort, and no severe AEs were reported in TGP group. Meanwhile, six trials showed statistically insignificant differences between TGP + IS and IS in AEs (P = 0.76). Conclusions: Improving the lacrimal gland secretion (Schirmer's test) is the prominent function of TGP compared with PBO. TGP + IS can improve the clinical symptoms, such as lacrimal and salivary gland secretion function (Schirmer's test, salivary flow rate), inflammatory indices (ESR, CRP, and RF) and immunoglobulins (γ-globulin, IgG, IgA, and IgM) on the basis of IS monotherapy. In addition, TGP has an acceptable safety profile and AEs were not increased when TGP combined with IS in pSS. Therefore, TGP can be considered to be a potentially valid and safe drug for the treatment of pSS in the clinic. In view of the limitations of the included trials, the potential beneficial effectiveness and safety of TGP need additional high-quality, multi-center, and large-scale RCTs to assess its use in pSS treatment.

Total Glycosides of Peony Protects Against Inflammatory Bowel Disease by Regulating IL-23/IL-17 Axis and Th17/Treg Balance

Inflammatory bowel disease (IBD) is a group of autoimmune diseases, including ulcerative colitis and Crohn’s disease, characterized by nonspecific inflammation in the gut. Total glycoside of peony (TGP) has been widely used for treatment of autoimmune diseases because of its pharmacological effects. However, it is lack of depth in whether TGP regulate T helper 17 cell (Th17) / T regulatory cell (Treg) immune balance or interleukin 23 (IL-23) / IL-17 axis to achieve the goal of treating IBD. Hence, the aim of this study was to investigate the effects of TGP on experimental colitis mice and the related mechanisms. In the present study, we demonstrated that administration of TGP effectively attenuates colonic inflammation of TNBS-induced colitis mice, mainly reflected in significantly improved clinical parameters, reduced inflammatory response and myeloperoxidase (MPO) activity, even stronger systemic immune ability and effective improvement of Th17/Treg immune disorders. In addition, there was a stronger immunosuppressive ability in a positive cluster of differentiation 4 (CD4[Formula: see text]) T-lymphocytes from the TGP treated mouse colon, characterized by the inhibition of high levels of inflammatory factors and increased regulatory T cells. Importantly, high-dose TGP has similar therapeutic effects as salicylazosulfapyridine (SASP) on IBD treatment. The potential mechanisms might be, at least in part, related to the adjustment of imbalance of Th17/Treg cells and the inhibition of IL-23/IL17 inflammatory signal axis.

All-Trans Retinoic Acid Induces CD4+CD25+FOXP3+ Regulatory T Cells by Increasing FOXP3 Demethylation in Systemic Sclerosis CD4+ T Cells

Background

Retinoic acid (RA) is an active metabolite of vitamin A and has been reported to improve the clinical symptoms of patients with systemic sclerosis (SSc). However, the mechanism of RA in the prevention of SSc remains unclear. Regulatory T cells (Tregs) are a subpopulation of T cells with immunosuppressive activity. The quantitative and functional defects of Tregs may mediate the immune dysfunction in SSc. The addition of all-trans retinoic acid (ATRA) to human naïve CD4+ cells could promote the maturation of Tregs and increase the stable expression of Foxp3. In this study, we explored the role of RA on Tregs in SSc CD4+ T cells and its possible epigenetic mechanisms, so as to further understand the mechanisms of RA on SSc.

Methods

CD4+ T cells were isolated from peripheral blood of SSc and treated with or without ATRA and/or transforming growth factor-β (TGF-β). The percentage of CD4+CD25+FOXP3+ Tregs was counted by flow cytometry. FOXP3 mRNA and protein levels were measured by quantitative real-time reverse transcriptase polymerase chain reaction and Western blotting, respectively. Bisulfite sequencing was performed to determine the methylation status of the FOXP3 proximal promoter sequences.

Results

The expression of Tregs and FOXP3 in CD4+ T cells from patients with SSc increased in response to ATRA. Moreover, combined stimulation with ATRA and TGF-β resulted in the enhancement of these effects. Further studies revealed that stimulation with ATRA increased the expression of FOXP3 in SSc CD4+ T cells by downregulating FOXP3 promoter methylation levels.

Conclusions

ATRA acts as an inducer of Treg response in SSc CD4+ T cells via demethylation of the FOXP3 promoter and activation of FOXP3 expression. This may be one of the molecular mechanisms for ATRA, and therefore, RA can be used for the treatment of SSc.

Paeoniflorin ameliorates collagen-induced arthritis via suppressing nuclear factor-κB signalling pathway in osteoclast differentiation

Paeoniflorin (PF), extracted from the root of Paeonia lactiflora Pall, exhibits anti-inflammatory properties in several autoimmune diseases. Osteoclast, the only somatic cell with bone resorbing capacity, was the direct cause of bone destruction in rheumatoid arthritis (RA) and its mouse model, collagen-induced arthritis (CIA). The objective of this study was to estimate the effect of PF on CIA mice, and explore the mechanism of PF in bone destruction. We demonstrated that PF treatment significantly ameliorated CIA through inflammatory response inhibition and bone destruction suppression. Furthermore, PF treatment markedly decreased osteoclast number through the altered RANKL/RANK/OPG ratio and inflammatory cytokines profile. Consistently, we found that osteoclast differentiation was significantly inhibited by PF through down-regulation of nuclear factor-κB activation in vitro. Moreover, we found that PF suppressed nuclear factor-κB activation by decreasing its translocation to the nucleus in osteoclast precursor cells. Taken together, our new findings provide insights into a novel function of PF in osteoclastogenesis and demonstrate that PF would be a new therapeutic modality as a natural agent for RA treatment and other autoimmune conditions with bone erosion.

Urinary and Serum Metabolomics Analyses Uncover That Total Glucosides of Paeony Protect Liver against Acute Injury Potentially via Reprogramming of Multiple Metabolic Pathways

Total glucosides of paeony (TGP) have been confirmed to be hepatoprotective. However, the underlying mechanism is largely unclear. In this study, we investigated the metabolic profiles of urine and serum in rats with carbon tetrachloride- (CCl₄-) induced experimental liver injury and TGP administration by using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The vehicle or a single dose of TGP was intragastrically administered to Wistar rats once a day for 14 consecutive days. To induce ALI, 50% CCl₄ was injected intraperitoneally into these rats 2 hours after the last time administration of saline of TGP at the 14th day. The results indicated that TGP administration could protect rats from CCl₄-induced ALI and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation, as well as hepatocyte apoptosis and inflammation. Furthermore, metabolomics analysis showed that TGP treatment significantly attenuated CCl₄-triggered deregulation of multiple metabolites in both urine and serum, including glycine, alanine, proline, and glutamine. Metabolite set enrichment and pathway analyses demonstrated that amino acid cycling and glutathione metabolism were two main pathways involved in CCl₄-induced experimental liver injury and TGP administration. Taken together, these findings revealed that regulation of metabolites potentially plays a pivotal role in the protective effect of TGP on ALI.

Paeoniflorin attenuates incipient diabetic nephropathy in streptozotocin-induced mice by the suppression of the Toll-like receptor-2 signaling pathway

Toll-like receptors (TLRs) may be involved in diabetic nephropathy (DN). Paeoniflorin (PF) is an effective Chinese traditional medicine with anti-inflammatory and immunoregulatory effects that may inhibit the TLR2 signaling pathway. In this study, we investigated the effects of PF on the kidneys of mice with streptozotocin-induced type 1 diabetes mellitus using TLR2 knockout mice (TLR2^−/−) and wild-type littermates (C57BL/6J-WT). After 12 weeks of intraperitoneal injection of PF at doses of 25, 50, and 100 mg/kg once a day, diabetic mice had significantly reduced albuminuria and attenuated renal histopathology. These changes were associated with substantially alleviated macrophage infiltration and decreased expression of TLR2 signaling pathway biomarkers. These data support a role of TLR2 in promoting inflammation and indicate that the effect of PF is associated with the inhibition of the TLR2 pathway in the kidneys of diabetic mice. PF thus shows therapeutic potential for the prevention and treatment of DN.

Total glucosides of paeony ameliorates TNBS‑induced colitis by modulating differentiation of Th17/Treg cells and the secretion of cytokines

The imbalance between effector CD4+ T helper 17 (Th17) and regulatory CD4+ T cells (Treg) cells and their associated cytokines, have been associated with the pathogenesis of inflammatory bowel disease (IBD). Total glycosides of paeony (TGP) is an alternative immunomodulatory agent that is widely used for the treatment of autoimmune diseases. The present study aimed to evaluate the modulatory effect of TGP in a rat model of colitis induced by 2,4,6‑trinitrobenzene sulfonic acid (TNBS). TGP was administered intragastrically 24 h after the TNBS intrarectal instillation for 7 days. TGP treatment ameliorated the clinical status and reversed the histopathologic severity of acute TNBS colitis. Furthermore, TGP inhibited the levels of Th17‑associated cytokines interleukin (IL)‑17, IL‑6, tumor necrosis factor‑α, whereas the expression levels of Treg‑associated cytokines IL‑10, transforming growth factor‑β in the plasma, colon, spleen and mesenteric lymph nodes (MLN). Additionally, TGP reduced the percentage of Th17 cells; however, the proportion of Treg cells in the spleen and MLN was increased. The present study also observed a suppression of Th17‑associated transcription factor, termed retinoid‑related orphan receptor‑γt (ROR‑γt). However, expression of the Treg‑associated transcription factor forkhead boxp3 was increased in the TGP treatment group. Therefore, the present findings suggest that TGP has a regulatory role in modulating the balance of Th17 and Treg cells to ameliorate the TNBS‑induced colitis and support the strategy of using TGP to treat IBD.

Total glucosides of paeony for rheumatoid arthritis: A systematic review of randomized controlled trials

BACKGROUND

Total glucosides of paeony (TGP) is commonly used to treat rheumatoid arthritis (RA) in China. However, clinical practice hasn't been well informed by evidence from appropriately conducted systematic reviews. This PRISMA-compliant systematic review aims at examining the effectiveness and safety of TGP for RA.

METHODS

Randomized controlled trials (RCTs) comparing TGP with placebo, no treatment, or disease-modifying antirheumatic drugs (DMARDs) for patients with RA were retrieved by searching seven databases. Primary outcomes included disease improvement and disease remission. Secondary outcomes included adverse effects, pain, health-related quality of life, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Data extraction and analyses were conducted according to the Cochrane standards. We assessed risk of bias for each included studies and quality of evidence on pre-specified outcomes.

RESULTS

Eight studies enrolling 1209 patients with active RA were included in this systematic review. On the basis of traditional DMARD(s), TGP might be beneficial for patients with RA in improvement of American College of Rheumatology (ACR) 20 response rate, ACR 50 response rate, ACR70 response rate, and in reduction of adverse effects, compared with no treatment. The overall methodological quality of included studies and the quality of evidence for each outcome were limited.

CONCLUSIONS

Current trials suggested potential benefits of TGP for RA on the basis of traditional DMARD(s). Therefore, TGP may be a good choice for RA as an adjuvant therapy. However, considering the limited methodological quality and strength of evidence, high-quality RCTs are warranted to support the use of TGP for RA.

Essential oil-mediated glycerosomes increase transdermal paeoniflorin delivery: optimization, characterization, and evaluation in vitro and in vivo

In this study, a novel glycerosome carrier containing essential oils was prepared for topical administration of paeoniflorin (PF) to enhance its transdermal drug delivery and improve drug absorption in the synovium. The formulation of glycerosomes was optimized by a uniform design, and the final vehicle was composed of 5% (w/v) phospholipid, 0.6% (w/v) cholesterol, and 10% (v/v) glycerol, with 2% (v/v) Speranskia tuberculata essential oil (STO) as the transdermal enhancer. The in vitro transdermal flux of PF loaded in the STO-glycerosomes was 1.4-fold, 1.6-fold, and 1.7-fold higher than those of glycerosomes, liposomes, and tinctures, respectively. In vivo studies showed that the use of STO-glycerosomes was associated with a 3.1-fold greater accumulation of PF in the synovium than that of common glycerosomes. This finding was confirmed by in vivo imaging studies, which found that the fluorescence intensity of Cy5.5-loaded STO-glycerosomes in mice knee joints was 1.8-fold higher than that of the common glycerosomes 5 h after administration. The glycerosomes mediated by STO exhibited considerable skin permeability as well as improved drug absorption in the synovium, indicating that STO-glycerosomes may be a potential PF transdermal delivery vehicle for the treatment of rheumatoid arthritis caused by synovium lesions.

New Insights into Regulatory T Cells: Exosome- and Non-Coding RNA-Mediated Regulation of Homeostasis and Resident Treg Cells

Regulatory T (Treg) cells are a group of cells that are heterogeneous in origin and in functional activity. Treg cells comprise a necessary balance to adaptive immune responses. As key regulators of self-tolerance, Treg cells have been involved in a series of pathologic processes and considered as therapeutic targets. Here, we summarize recent research regarding Treg cell origins and their functional classification, highlight the role of exosomes and non-coding RNA in modulating Treg cell homeostasis, and discuss the current understanding of resident Treg cells.

Paeoniflorin inhibits high glucose-induced macrophage activation through TLR2-dependent signal pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin(PF), extracted from the root peeled of Paeonia lactiflora Pall(Family: Ranunculaceae), has therapeutic potential in many animal models of inflammatory diseases.

AIM OF THE STUDY

Although the anti-inflammatory efficacy of PF has been well illustrated in several animal models, whether it could attenuate diabetic nephropathy and detailed mechanisms are still obscure. Till now, accumulating evidence has proposed the pivotal role of toll-like receptors (TLRs) in renal inflammation in diabetic patients. In this setting, the current study aimed to investigate the effects and underlying mechanism of PF on high glucose-induced activation of toll like-receptor 2 (TLR2) signaling in macrophages.

MATERIALS AND METHODS

Bone marrow-derived macrophages (BMDM) were isolated from male Tlr2^tm1kir (TLR2-/-) mice and wild-type littermates (C57BL/6JWT). The level of TLR2 and activation of downstream signaling were evaluated in response to 30mmol/L high glucose (HG)-containing medium. Macrophages behaviors, which include cell viability, migration and inflammatory cytokines production, were also determined.

RESULTS

PF suppressed HG-induced production of TLR2, activation of downstream signaling and synthesis of inducible nitric oxide synthase (iNOS). PF could further inhibit MyD88-dependent pathway in HG-induced models in which TLR2 was knocked out. Moreover, deletion of TLR2 inhibited the HG-induced activation of MyD88-dependent pathway, but not TIR domain containing adapter inducing interferon-β (Trif) signal pathway in BMDMs. As HG stimulation polarizes macrophages into M1 phenotype, treatment of PF or knockout of TLR2 significantly reduces M1 markers on the membrane of macrophages. Additionally, levels of inflammatory cytokines and iNOS were remarkably reduced in response to PF or TLR2 deficiency.

CONCLUSION

Collectively, these data demonstrated that HG activated macrophages primarily through TLR2-dependent mechanisms which aggravated the severity of renal inflammation and eventually contributed to DN. Additionally, PF might be applied as a potential therapeutic agent in the battle against progressive DN.

Clinical and immunological consequences of total glucosides of paeony treatment in Sjögren's syndrome: A randomized controlled pilot trial

BACKGROUND

The total glucosides of paeony (TGP) can inhibit inflammation and alleviate symptoms in autoimmune diseases. This study investigated the clinical and immunological consequences of TGP treatment in patients with primary Sjögren's syndrome (SS).

METHODS

We conducted a randomized, double-blinded, placebo-controlled clinical trial in 45 patients with primary SS. Patients were randomized at 2:1 ratio to either TGP group (n=29) or placebo group (n=16) and followed up for 24weeks. The primary outocme was the European League Against Rheumatism Sjögren's Syndrome Patient Reported Index (ESSPRI). The secondary outcomes were stimulated and unstimulated salivary flow rate, Schirmer's test and erythrocyte sedimentation rate (ESR), immuneglobulin (Ig), anti-nuclear antibody (ANA), anti-SSA, and anti-SSB. The proportions of B cells in peripheral blood and the levels of serum inerleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and B cell activating factor belonging to the TNF family (BAFF) were measured at baseline and at the end of follow up of 24weeks.

RESULTS

The average score of ESSPRI in both groups had no statistical significance at 24th week. The mean of ESSPRI in the dry-mouth part of questionnaire in patients who scored 3 to 6 points was significantly reduced in the TGP group changed from (4.81±0.60) at baseline to (4.20±1.46) (P=0.027) at week 24. Stimulated salivary flow rate increased at week 24 from (1.80±0.39) to (2.01±0.51) (P=0.031) and unstimulated salivary flow rate increased from (0.65±0.46) to (0.78±0.45) (P=0.011) in the TGP group, but the placebo group showed no significant difference. Erythrocyte sedimentation rate (ESR) was decreased significantly compared to the placebo group at 12- and 24-week from (40.9±18.0) to (29.4±12.2) (P=0.003) and (30.4±17.3) (P=0.024). The percentage of naive B cells decreased at week 24 in the TGP group from (77.34±12.20) to (64.59±15.60) (P=0.005) while memory B cells increased from (21.79±11.97) to (34.21±15.48) (P=0.006) respectively. The concentrations of TNF-α and IFN-γ decreased in the TGP group at week 24 from (32.51±26.67) to (24.22±13.56) (P=0.017) and (10.71±8.94) to (6.55±4.88) (P=0.022), respectively. No significant difference in ANA titer, anti-SSA antibodies, anti-SSB antibodies, C3 concentration or C4 concentration was observed between the two groups.

CONCLUSION

TGP appears to improve the glandular secreting function and decrease the level of inflammatory cytokines.

Paeoniflorin suppresses inflammatory response in imiquimod-induced psoriasis-like mice and peripheral blood mononuclear cells (PBMCs) from psoriasis patients

Psoriasis is one of the most common immune-mediated chronic inflammatory skin disorders, characterized by hyperproliferation of keratinocytes, dilation and growth of dermal capillary vasculature, and cellular infiltration of T cells, dendritic cells (DCs), and neutrophils. Paeoniflorin (PF), the principal component of total glucosides of paeony (TGP), displays anti-inflammatory and antioxidant properties in several animal models. In this study, we investigated the anti-inflammatory effects and mechanisms of PF in imiquimod (IMQ)-induced psoriasis-like mouse model. The effects of PF on inflammatory cytokine expression in peripheral blood mononuclear cells (PBMCs) from patients with psoriasis vulgaris were also observed. Our results indicated that PF effectively attenuated the clinical and histopathologic changes in IMQ-induced psoriasis-like mouse model. Furthermore, PF reduced the infiltration of T cells, CD11c+DCs, and neutrophils in lesional skin. In addition, PF also significantly decreased the mRNA expression of inflammatory cytokines, such as IL-17, INF-γ, IL-6, and TNF-α, in IMQ-induced psoriasis-like mouse model and PBMCs from patients with psoriasis vulgaris. Hence, our data suggest that PF can inhibit leukocyte infiltration and decrease the expression of inflammatory cytokines such as IL-17, INF-γ, IL-6, and TNF-α. PF might be a candidate drug for the treatment of psoriasis.

Clinical study of total glucosides of paeony for the treatment of diabetic kidney disease in patients with diabetes mellitus

BACKGROUND AND AIM

Total glucosides of paeony (TGP), an active compound extracted from dried roots of Paeonia lactiflora Pall, have anti-inflammatory effects. This study investigated the efficacy and safety of TGP for treating diabetic kidney disease (DKD) in type 2 diabetes mellitus patients.

METHODS

An open-label, prospective, randomized, parallel-group, single-site study involving 76 patients with DKD. Patients were randomized into two groups: losartan group (n = 38), treated with losartan 100 mg/day for 6 months and TGP group (n = 38), treated with TGP 1800 mg/day and losartan 100 mg/day for 6 months. Serum hs-CRP, MCP-1, and TNF-α were determined before and after treatment. Urinary albumin excretion rate (UAER), fasting blood glucose, serum creatinine, and lipid profiles were examined.

RESULTS

At the end-point, UAER decreased in the TGP group compared with baseline. UAER in the losartan group decreased to a level lower than before treatment. The rate of decline in the losartan group was significantly lower than the TGP group. There were no significant differences in serum creatinine and albumin levels between TGP and losartan groups at the end-point. Serum hs-CRP, MCP-1, and TNF-α levels were significantly lower in both groups after treatment. After treatment, serum hs-CRP, MCP-1, and TNF-α in the TGP group decreased more than the losartan group. Positive correlations were observed between UAER and hs-CRP, MCP-1, and TNF-α. No statistically significant difference in side effects was observed between groups.

CONCLUSION

Our study showed that TGP treatment could reduce the albuminuria and inflammatory markers in type 2 diabetes mellitus patients with DKD.

The Efficacy and Safety of the Combination of Total Glucosides of Peony and Leflunomide for the Treatment of Rheumatoid Arthritis: A Systemic Review and Meta-Analysis

Objective. To evaluate the efficacy and safety of the total glucosides of peony (TGP) and leflunomide (LEF) for the treatment of rheumatoid arthritis (RA). Methods. Randomized controlled trials (RCTs) on the efficacy and safety of the combination of TGP and LEF versus LEF alone for the treatment of RA were retrieved by searching PubMed, EMBASE, Cochrane Library, the China National Knowledge Infrastructure database, and Wanfang database. Results. Eight RCTs including 643 RA patients were included in the present meta-analysis. The quality of included studies was poor. The levels of ESR (P < 0.0001), CRP (P < 0.0001), and RF (P < 0.0001) in RA patients who received the combination of TGP and LEF were significantly lower than RA patients who received LEF therapy alone. The pooled results suggest that the combination of TGP and LEF caused less abnormal liver function than LEF alone (P = 0.02). No significant difference in the gastrointestinal discomfort was identified between the combination of TGP and LEF and LEF alone groups (P = 0.18). Conclusion. The combination of TGP and LEF in treatment of RA presented the characteristics of notably decreasing the levels of laboratory indexes and higher safety in terms of liver function. However, this conclusion should be further investigated based on a larger sample size.

Total glucosides of paeony for rheumatoid arthritis: a protocol for a systematic review

INTRODUCTION

Total glucosides of paeony (TGP) is a natural plant extract, which is widely used in China for treating rheumatoid arthritis (RA). Many relevant randomised controlled trials (RCTs) of TGP for RA are available, but they have not been systematically reviewed. This systematic review aims to examine the effectiveness and safety of TGP in patients with RA.

METHODS AND ANALYSES

We will search for RCTs of TGP in the treatment of RA, performed up until February 2016, in PubMed, Embase, Cochrane Central Register of Controlled Trials, and four Chinese databases (Chinese Biomedical Database, China National Knowledge Infrastructure, Wanfang Database and Chinese Scientific Journal Database). Trial registers and reference lists of retrieved articles will also be searched to identify potential articles. RCTs comparing TGP with placebo, no treatment, or disease-modifying antirheumatic drugs for patients with RA will be retrieved. The primary outcomes will be disease improvement and disease remission. The secondary outcomes will be surrogate outcomes, symptoms, adverse effects, and quality of life. Two reviewers will independently extract data on participants, interventions, comparisons, outcomes, etc. The methodological quality of each included study will be evaluated using the Cochrane risk of bias tool, and the strength of evidence on prespecified outcomes will be assessed in accordance with the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. Review Manager 5.3 software will be used for data analyses. Meta-analyses will be performed if the data are sufficiently homogeneous, both statistically and clinically. Possible publication bias will also be checked using funnel plots once the number of included studies is sufficient.

ETHICS AND DISSEMINATION

Ethics approval is not required, as this study will not involve patients. The results of this study will be submitted to a peer-reviewed journal for publication, to inform both clinical practice and further research.

TRIAL REGISTRATION NUMBER

CRD42015026345.

Unique immunomodulatory effect of paeoniflorin on type I and II macrophages activities

It has been widely accepted that macrophages are divided into M1 "pro-inflammatory" macrophages and M2 "anti-inflammatory" macrophages and an uncontrolled macrophage polarization plays an important role in the pathogenesis of different diseases. As the main substance of total glucosides of peony, paeoniflorin (PF), has been widely used to treat autoimmune and autoinflammatory diseases for years. Mechanistically, PF has been found to alter activities of many immune cells, which could further reduce inflammation and tissue damage. However, whether and how PF affects macrophages activities in vitro remains unknown. In current study, using M1 and M2 cells generated from mouse bone marrow precursors, we explored the role of PF in regulating M1/M2 cells activity in vitro. The results showed that PF inhibited LPS-induced M1 activity by reducing iNOS expression and NO production via decreasing LPS/NF-κB signaling pathway; whereas, PF enhanced IL-4-provoked M2 function by up-regulating Arg-1 production and activity via increasing IL-4/STAT6 signaling pathway. Our new finding indicates that PF can suppress M1 cells activity and enhance M2 cells function simultaneously, which could help to ameliorate autoimmune and autoinflammatory diseases in clinical treatment.

Total glucosides of peony attenuates experimental autoimmune encephalomyelitis in C57BL/6 mice

Total glucosides of peony (TGP), an active compound extracted from the roots of Paeonia lactiflora Pall, has wide pharmacological effects on nervous system. Here we examined the effects of TGP on experimental autoimmune encephalomyelitis (EAE), an established model of multiple sclerosis (MS). The results showed that TGP can reduce the severity and progression of EAE in C57 BL/6 mice. In addition, TGP also down-regulated the Th1/Th17 inflammatory response and prevented the reduced expression of brain-derived neurotrophic factor and 2',3'-cyclic nucleotide 3'-phosphodiesterase of EAE. These findings suggest that TGP could be a potential therapeutic agent for MS.

Paeoniflorin inhibits skin lesions in imiquimod-induced psoriasis-like mice by downregulating inflammation

Psoriasis is a common chronic immune-mediated inflammatory disease. It is well known that macrophages, neutrophils and T-helper 1 (Th1)/T-helper 17 (Th17) cells play important roles in skin lesions by provoking inflammation. Paeoniflorin (PF) is the major effective component extracted from the root of Paeonia lactiflora, which has been widely used in China to treat inflammatory and autoimmune diseases, including psoriasis. Although PF shows a clinical therapeutic effect on psoriasis patients, how PF affects infiltrated immune cells in psoriasis skin lesions is still unknown. In this study, using a generated imiquimod (IMQ)-induced psoriasis-like mouse model, we found that PF ameliorates inflammation and skin lesions. Subsequent analyses showed that PF decreases the number of F4/80(+)CD68(+) macrophages and their related cytokine production (TNF-α, IL-1β, IL-6, IL-12 and inducible nitric oxide synthase (iNOS)) in the skin of IMQ-challenged mice. Moreover, PF suppresses the number of CD11b(+)Gr-1(+) neutrophils and the expression of macrophage inflammatory protein-2 (MIP-2; a counterpart of human IL-8, which is responsible for the recruitment of neutrophils in mice). Finally, PF also down-regulates Th1- and Th17-related cytokine expression. Therefore, our new findings reveal that PF alleviates psoriatic skin lesions by inhibiting inflammation, which provides new insights into the immunomodulatory effect of PF in psoriasis treatment.

Epigenetics in the treatment of systemic lupus erythematosus: potential clinical application

The current treatments of systemic lupus erythematosus (SLE) have been based on the use of immunosuppressive drugs which are linked to serious side effects. The more effective therapeutic approaches with minimal or no side effects for SLE patients are hard to develop, mainly due to the complexity of the disease. The discovery of pharmacoepigenetics provides a new way to solve this problem. Epigenetic modifications can influence drug efficacy by altering gene expression via changing chromatin structure. Although still in early development, epigenetic studies in SLE are expected to reveal novel therapeutic targets and disease biomarkers in autoimmunity. For example, miRNAs, which have been identified to govern many genes including drug targets, are altered in disease development and after drug administration. This review aims to present an overview of current epigenetic mechanisms involved in the pathogenesis of SLE, and discuss their potential roles in clinical and pharmacological applications.

Peripheral whole blood FOXP3 TSDR methylation: a potential marker in severity assessment of autoimmune diseases and chronic infections

Immune dysregulation is a cardinal feature of autoimmune diseases and chronic microbial infections. In particular, regulatory T cells are downregulated in autoimmune diseases while upregulated in chronic microbial infections. FOXP3 is the master regulator of Treg development. Treg-specific demethylated region (TSDR) is a highly conserved locus on the FOXP3 gene that is fully demethylated in natural Tregs but methylated in effector T cells. In our study, we used high resolution melt-polymerase chain reaction (HRM-PCR) to determine the FOXP3 TSDR methylation status in autoimmune diseases and chronic microbial infections. We found that FOXP3 TSDR to have the highest mean melting temperature (highly methylated) in active SLE patients compared to all the other groups (p < 0.001). The psoriasis group also had a significantly high mean melting temperature (78.62 ± 0.20) when compared with the inactive SLE group (78.49 ± 0.29, p < 0.05) and control group (78.44 ± 0.25, p < 0.01). There was no significant difference in melting temperature between inactive SLE and healthy controls. Disease activity in SLE was directly associated with methylation of the FOXP3 TSDR. On the other hand, patients with chronic microbial infections had significantly lower FOXP3 TSDR mean melting temperature (demethylated) when compared with healthy controls (78.28 ± 0.21 vs 78.44 ± 0.25, p < 0.05). Our results suggest that the use of HRM-PCR to detect FOXP3 TSDR methylation status is a reliable and easy method to predict natural regulatory T cell levels in peripheral blood in different disease conditions. Determining FOXP3 TSDR methylation status can be a useful tool in diagnosis, and monitoring the severity of autoimmune diseases and chronic microbial infections.

Critical role of DNA methylation in the pathogenesis of systemic lupus erythematosus: new advances and future challenges

Systemic lupus erythematosus (SLE) is a systemic multi-organ autoimmune disease with different immunological characteristics and clinical manifestations characterized by an autoantibody response to nuclear and cytoplasmic antigens; the etiology of this disease remains largely unknown. Most recent genome-wide association studies demonstrate that genetics significantly predispose to SLE onset, but the incomplete disease concordance rates between monozygotic twins indicates a role for other complementary factors in SLE pathogenesis. Recently, much evidence strongly supports other molecular mechanisms involved in the regulation of gene expression ultimately causing autoimmune disease, and several studies, both in clinical settings and experimental models, have demonstrated that epigenetic modifications may hold the key to a better understanding of SLE initiation and development. DNA methylation changes the structure of chromatin, being typically able to modulate the fine interactions between promoter-transcription factors and encoding genes within the transcription machinery. Alteration in DNA methylation has been confirmed as a major epigenetic mechanism that may potentially cause a breakdown of immune tolerance and perpetuation of SLE. Based on recent findings, DNA methylation treatments already being used in oncology may soon prove beneficial to patients with SLE. We herein discuss what we currently know, and what we expect in the future.

Total glucosides of paeony prevents juxta-articular bone loss in experimental arthritis

Background

Total glucosides of paeony (TGP) is a biologically active compound extracted from Paeony root. TGP has been used in rheumatoid arthritis therapy for many years. However, the mechanism by which TGP prevents bone loss has been less explored.

Methods

TGP was orally administered for 3 months to New Zealand rabbits with antigen-induced arthritis (AIA). Digital x-ray knee images and bone mineral density (BMD) measurements of the subchondral knee bone were performed before sacrifice. Chondrocytes were observed using transmission electron microscopy (TEM). Histological analysis and mRNA expression of receptor activator of nuclear factor-B ligand (RANKL) and osteoprotegerin (OPG) were evaluated in joint tissues.

Results

The BMD value in TGP rabbits was significantly higher compared with that seen in the AIA model rabbits. In addition, the subchondral bone plate was almost completely preserved by TGP treatment, while there was a decrease in bone plate integrity in AIA rabbits. There was less damage to the chondrocytes of the TGP treated group. Immunohistochemical examination of the TGP group showed that a higher percentage of TGP treated chondrocytes expressed OPG as compared to the chondrocytes isolated from AIA treated animals. In contrast, RANKL expression was significantly decreased in the TGP treated group compared to the AIA group. In support of the immunohistochemistry data, the expression of RANKL mRNA was decreased and OPG mRNA expression was enhanced in the TGP group when compared to that of the AIA model group.

Conclusion

These results reveal that TGP suppresses juxta-articular osteoporosis and prevents subchondral bone loss. The decreased RANKL and increased OPG expression seen in TGP treated animals could explain how administration of TGP maintains higher BMD.

DNA methylation impairs TLR9 induced Foxp3 expression by attenuating IRF-7 binding activity in fulminant type 1 diabetes

Fulminant type 1 diabetes (FT1D) is an extremely aggressive disease characterized by the abrupt onset of insulin-deficient hyperglycemia. However, the precise mechanisms underlying disease etiology almost remain unclear. As mice deficient in regulatory T cells (Tregs) are prone to the development of an FT1D-like phenotype, we thus investigated whether FT1D patients manifest Treg deficiency and explored the related mechanisms. We first noted a significant reduction for Foxp3 and CTLA4 expression levels in PBMCs of FT1D patients. IRF-7 was found to selectively bind to the Foxp3 promoter, and by which it promotes Foxp3 transcription. Therefore, ectopic IRF-7 expression significantly promoted Foxp3 and CTLA4 expression in PBMCs, while knockdown of IRF-7 manifested opposite effect. Importantly, stimulation of PBMCs with CpG ODN, a ligand for TLR9, significantly induced Foxp3 expression, demonstrating that TLR9 signaling positively regulates Treg development. However, knockdown of IRF-7 expression almost completely diminished the enhancing effect of TLR9 signaling on Foxp3 expression, suggesting that IRF-7 is a downstream molecule of TLR9 signaling and is essential for TLR9 induced Treg generation. Of interestingly note, the Foxp3 promoter in FT1D patients was hypermethylated, indicating that DNA methylation could be a causative factor responsible for the reduced Foxp3 expression in FT1D patients. Indeed, our mechanistic studies revealed that DNA methylation blocked IRF-7 binding to the Foxp3 promoter. Together, our data support the notion that environmental insults in genetic predisposed subjects trigger Foxp3 promoter hypermethylation, which then prevents IRF-7 binding to the Foxp3 promoter and impairs Treg development/functionality contributing to the pathogenesis of FT1D.

The critical importance of epigenetics in autoimmunity

Autoimmune diseases are characterized by aberrant immune responses against healthy cells and tissues, in which a given individual's genetic susceptibilities play a central role; however, the exact mechanisms underlying the development of these conditions remain for the most part unknown. In recent years, accumulating evidence has demonstrated that, in addition to genetics, other complementary mechanisms are involved in the pathogenesis of autoimmunity, in particular, epigenetics. Epigenetics is defined as stable and heritable patterns of gene expression that do not entail any alterations to the original DNA sequence. Epigenetic mechanisms primarily consist of DNA methylation, histone modifications and small non-coding RNA transcripts. Epigenetic marks can be affected by age and other environmental triggers, providing a plausible link between environmental factors and the onset and development of various human diseases. Because of their primary function in regulating timely gene expression, epigenetic mechanisms offer potential advantages in terms of interpreting the molecular basis of complicated diseases and providing new promising therapeutic avenues for their treatment. The present review focuses on recent progress made in elucidating the relationship between epigenetics and the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, primary Sjögren's syndrome, primary biliary cirrhosis, psoriasis and type 1 diabetes.